The present invention relates to a mold for a rubber tire and more particularly to a vent structure which is especially suitable for a tire sidewall made of a thin sidewall rubber on the carcass.
In general, during manufacturing a pneumatic tire, a raw tire is vulcanized in a mold. As the surface of the raw tire closely contacts with the molding faces of the mold, the tire is provided with a designed desired shape. Therefore, to discharge the air between the mold and the raw tire, small vent holes usually having a diameter of 0.1 to 2 mm are formed in the molding faces. Such vent holes more or less cause spews on the surface of the vulcanized tire.
If spews are formed on the tread face, it would not be a significant matter because they would be easily removed during running and under cover of unevenness of the tread face due to tread grooves. However, such action and effect cannot be expected with respect to the spews on the sidewall. Therefore, the appearance of the tire is degraded.